WASHINGTON -- For 12 minutes, raw emotions supplanted dry legal principles as 13 prosperous white senators, members of the world's most exclusive club, listened intently to Clarence Thomas recall how his grandfather was called "boy," and how his grandmother was denied the use of a bathroom because of the color of her skin.

Before his grandparents took him in, he said, his voice choking with emotion as his audience sat silent, he and his mother and brother lived in a one-room tenement, shared a kitchen and relieved themselves in a broken-down privy.

It was, he said, "a life far removed in space and time from this room, this day and this moment . . . It was a world so vastly different from all this."

Ultimately, many believe, it is that stark contrast in class, race and background that will make it difficult for many Democratic senators to cast a vote against Thomas.

The Supreme Court nominee's voice choked as he spoke yesterday. His wife, Virginia Lamp Thomas, sat behind her husband, tears welling in her eyes and her lip quivering, with Jamal, his 19-year-old son by his first marriage, beside her. In the public gallery to the rear, her mother, Marjorie Lamp, dabbed at her eyes with a handkerchief.

Only Thomas' sister, Emma Mae Martin, a former welfare recipient he once publicly criticized, appeared unmoved.

When he and his brother were separated from Emma Mae, Thomas recalled, they left the tenement with all their belongings in two paper sacks.

The upbringing with his grandparents, he said, gave him the tools he needed to excel.

"I can still hear my grandfather: 'Y'all goin' to have mo' of a chance than me,' " Thomas said. "And he was right. He felt that if others sacrificed and created opportunities for us, we had an obligation to work hard, to be decent citizens, to be fair and good people. And he was right."

"You see, Mr. Chairman," he said, addressing Sen. Joseph R. Biden Jr., head of the Senate Judiciary Committee, only one of whose members was absent, "my grandparents grew up and lived their lives in an era of blatant segregation and overt discrimination. Their sense of fairness was molded in a crucible of unfairness."

Sen. John C. Danforth, R-Mo., an heir to the Ralston-Purina fortune, who introduced Thomas to the committee, helped delineate the gulf between their past lives and Thomas'.

"I hope that some time in the days ahead . . . someone will ask him not about unenumerated rights or the establishment clause, but about himself. What was it like to grow up under segregation? What was it like to be there when your grandfather was humiliated before your eyes? What was it like to be laughed at by seminarians because you are black?"

Danforth concluded: "Everyone in the Senate knows something about the legal issues before the Supreme Court. Not a single member of the Senate knows about being poor and black in America."